While Tallest Purple is army crawling in the vents to the AI server emergency shutdown/reset station, Tallest Red is rescuing the Earth’s liaison from the Massive’s garbage deposal. The ships AI goes haywire and misidentifies her as trash and sends her to the disposal pool and just in time too, as the meltdown sequence was about begin, if the electric shocks didn’t kill her then the acid effect would.
The blue goo they’re standing is called pulse acid It a type liquid chemical that Zim had developed when he was a scientist, it’s as harmless as water. Until an electric shock introduced to it then it turns into a dissolvent, but the disolving process is slow, needing up to a dozen shocks or more before it can dissolve an entire object, which is very useful in case someone fell in or threw out something important. the process can be stopped at the press of a button. Good thing everything in Disposal is manual control instead of AI controlled.